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Cryptosporidium parvum is a single-celled parasite (protozoan) which has caused some significant water-borne outbreaks of gastroenteritis in B.C. (e.g. Cranbrook, Kelowna and Penticton, 1996). It is not a serious health threat for people with a healthy immune system. However, as of 2009, there is no treatment that can eliminate this parasite from the body, so the immune system must remove it. Therefore, for people who are immunocompromised, it can cause prolonged illness.

Cryptosporidia are passed in the stools of animals, and can contaminate water supplies. They can form spores to survive when conditions are not good for their growth and survival, causing challenges for water treatment system operators. And, since cryptosporidiosis is primarily water-borne, this means that immunocompromised individuals mayneed to take special precautions with their drinking water (see 'Prevention' in the Overview).

Information for Health Professionals

Cryptosporidium parvum is a parasite that infects the intestinal tract. When a person gets sick from this infection it is called cryptosporidiosis.

Cryptosporidiosis is not an uncommon illness in B.C. and the world. Over the past 10 years (1999 to 2008), the number of infections per year has averaged 130 infections per year reported to the B.C. Centre for Disease Control.

Cryptosporidiosis may result in: 
  • frequent, watery diarrhea
  • stomach cramps
  • nausea
  • vomiting
  • mild fever and
  • dehydration.

Symptoms start an average of 7 days (range 2 to 10 days) after exposure to the parasite. Often a person can be infected and have no symptoms. Symptoms usually last for 1 to 2 weeks in people who are otherwise healthy. In some cases, symptoms can return after you have started to recover.

Cryptosporidiosis is spread by the fecal-oral route. Fecal material from infected humans or animals can get into our mouths by
  • consuming contaminated food or drink
  • contact with the feces of infected humans (e.g. changing diapers) that is not followed by proper hand washing
  • contact with the feces of domestic or wild animals, including pets and farm animals, that is not followed by proper hand washing.Pets may also have fecal matter on their hair or fur that is transferred to our hands when we touch them.
  • outbreaks are usually due to contamination in a water system
Cryptosporidiosis is commonly a water-borne disease. Cryptosporidia are very hardy organisms that survive for long periods of time in the environment including in cold water, since they have the ability to form a hardy spore (called an oocyst) that can survive when conditions for growth are not optimum.

There are no medications that can successfully remove the parasite. Only the body's immune system can remove it. Therefore, people with poorly functioning immune systems are at risk of more serious illness when they get cryptosporidiosis (e.g. severe dehydration). 

A microscopic examination of a stool sample will enable a diagnosis of cryptosporidiosis.

For individuals with a healthy immune system, the illness usually resolves on its own after a few weeks and no treatment is necessary. If symptoms are severe, last for several weeks or if you have a weak immune system, consult your healthcare provider for treatment advice. People with diarrhea should drink plenty of fluids to prevent dehydration.

If you think you have a cryptosporidium infection, see your family doctor for testing, advice and treatment. 

Cryptosporidia are passed in the feces; therefore, people with diarrhea which may be due to an infection should not go to work or school. 

If you are a food handler or health care worker it is possible for you to transmit cryptosporidiosis to others while carrying out your duties in these settings. Do not work while you have diarrhea or vomiting and do not return to work until 48 hours after your last loose stool or episode of vomiting. This time period will ensure you have a chance to recover and lessen the possibility of transmitting the infection to others. 

Children in day care who have diarrhea can be cared for temporarily in an area separate from other children until picked up by their parents. Children cannot return to day care until 48 hours after their last loose stool or episode of vomiting. To ensure proper hand washing, children in day cares should be supervised by an adult when washing their hands. 

When you recover you may excrete cryptosporidia in your stools for several weeks and possibly infect others. After using the toilet and before eating or preparing foods, wash your hands thoroughly with liquid soap and water.

If you are immune-compromised, find out what kind of treatment your water supply has. 

Refer to the information in HealthLink BC File #56: Weakened Immune Systems and Water-borne Infections.

  • If your local drinking water providere has issued a Boil Water Notice for your community water system, take the advice seriously.
  • Do not drink untreated surface water from a spring, stream, river, lake, pond or shallow well. Assume it is contaminated with animal feces. Boil or filter water from these sources that is used for
  1. drinking
  2. making ice cubes
  3. washing uncooked fruits and vegetables
  4. making baby formula
  5. brushing teeth
  6. rinsing dentures
  7. any purpose where consumption will occur without adequate heat treatment.
  • When camping, do not relieve yourself within 100 feet of a water source.
  • If you have a cryptosporidium infection, do not swim in lakes, ponds, streams, rivers, swimming pools and hot tubs while you have diarrhea and until at least 48 hours after the diarrhea has stopped. Avoiding this activity will help to ensure that other swimmers do not become infected.
  • Do not drink unpasteurized milk or juices.
    1. Before eating
    2. Before handling food
    3. After using the toilet or changing diapers
    4. After touching animals
  • Make sure children, particularly those who handle pets, wash their hands carefully before eating and on a regular basis if they suck their thumbs or put their hands in their mouths.
  • There are two methods to eliminate Cryptosporidia from water:
  1. Boiling: Bring water to a rolling boil for at least 1 minute and then allow it to cool. At elevations over 2,000 meters (6,562 feet) you should boil water for at least 2 minutes to disinfect. Boiling will not purify water that is obviously heavily polluted or chemically contaminated.
  2. Filtering: To effectively remove cryptosporidium cysts, filters must have an absolute pore size of 1 micron or be rated by the National Sanitation Foundation (NSF) for cyst removal. Cysts are 4 to 6 microns in length and will not pass through a filter pore of 1 micron. Some portable water treatment units used for camping meet the above requirements.

Jug-type water filters are not effective in removing cryptosporidia. Some built-in water filtration systems will remove cryptosporidia, but they need regular and thorough maintenance to work effectively. 

Other types of water treatment units, such as distillation units, reverse osmosis and combination (filtration and ultraviolet) units are also available. Check with local water purification suppliers or your local environmental health officer for more detailed information. 

Cryptosporidia are resistant to chlorine. Treating water with chlorine will NOT remove the parasite.

SOURCE: Cryptosporidium ( )
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